1. Field of the Invention
The present invention relates to facilitating control within Industry Standard Architecture (ISA) compatible laptop computers. Specifically, the invention involves a system for downloading instructions for access by a peripheral controller. The peripheral controller executes the downloaded instructions to emulate a conventional INTEL 8042 or 8742 series peripheral controller, and also to provide other functions not conventionally provided by the 8042 or 8742 series circuits.
2. Description of the Related Art
Conventional ISA (i.e. IBM-AT) compatible computers utilize an integrated circuit (IC) intelligent peripheral microcontroller to perform various control functions between a master processor (the host--the master central processing unit and supporting resources) and various peripheral devices. Typical I/O functions performed by the peripheral microcontroller involve scanning a keyboard and providing an interface between peripheral devices and the host. The microcontroller interfaces these peripheral devices with the standard ISA data and control busses. The microcontroller provides registers which enable it to function as one peripheral device to the master processor. The microcontroller performs the basic I/O functions for other peripheral devices so the host does not have to use processor time to perform these functions. The host only communicates with the peripheral microcontroller which performs the processing necessary to support the other peripheral devices.
The INTEL 8042 and 8742 integrated circuits are common peripheral microcontrollers for the ISA compatible computer architecture. The use of the 8042 and the 8742 integrated circuits in laptop computers is undesirable because these integrated circuits utilize older technology which consumes too much power. For instance, the INTEL 8742 is a 50 mA IC.
Under the conventional design, the peripheral controllers such as the INTEL 8042 or 8742 in INTEL-based systems perform fixed functions. The instructions to perform these functions are generally contained in a read-only memory (ROM). This approach does not allow for peripheral devices which do not conform to the standard functions performed by a conventional peripheral controller such as the 8042 or 8742.
It is desirable to have a peripheral controller which may be programmed to emulate the conventional INTEL 8042 or 8742 series of integrated circuits and also be programmed to provide further functions, such as power management routines. Moreover, it is desirable to configure a peripheral controller to manage devices with non-standard protocols or devices which do not conform to the standard functions provided by the conventional peripheral controllers.
A new peripheral controller is needed which receives instructions downloaded from the host instead of only having access to the limited fixed functions as defined in the ROM. This allows downloading of new instructions or patches of segmented instruction codes to accommodate other peripheral devices or other functions not provided by the conventional 8042 or 8742 series of integrated circuits.